With its opening exhibition in October, 1987, showing "Publiziertes und Unpubliziertes" ("Published and Unpublished Works") by Dieter Roth, Portikus began its exhibition series presenting parallel to the Frankfurt book fair an artist, who is especially committed to the book as an autonomous medium of artistic work. After Ilya Kabakov - 10 Albums - in 1988 and Lawrence Wiener last year, Portikus now presents the book projects of Sol Lewitt.

Sol Lewitt belongs, as does Lawrence Wiener, to the most important representatives of American conceptual art, a term Lewitt introduced into the debate in his Paragraphs and Sentences on Conceptual Art. His pictorial concept is based on the formal language developed concurrently by minimal art. In various media, Lewitt elaborated its reduced vocabulary based on elementary geometric and stereometric forms to serial structures. The presentation of the concept is in the foreground, while its physical realisation is secondary. "The idea itself, even if not turned into a visible form, is also a work of art just like any completed product. All stages in between - initial scribbles, sketches, drawings, unsuccessful works, models, studies, thoughts, conversations - are of interest. Those showing the artist's process of thought are often more interesting than the final result." (Paragraphs, 1966) This means that the formal and material aesthetics of the work steps back in favour of the concept, without, however, being excluded. This becomes especially evident in the coloured wall drawings; their visible sensuousness only seemingly contradicts the stringent conceptuality. The individual work is not directed towards rational relationships in regard to its visible qualities or its conceptual structure; rather, Lewitt is concerned with thematising such a relationship as simply antithetic. The logical, systematic variation of formal shapes is subordinated to the idea of a potential multitude of systems of order.

Next to giving these ideas shape in sculptures and wall drawings, Lewitt, since the mid-sixties, has been using the book as a medium for presenting his concepts. For Lewitt, as for other artists at that time, the book was an adequate medium for realising one's ideas and expanding the traditional forms of presentation in exhibitions. A necessity also to be seen in the context of developing new artistic practices and dimensions aimed at breaking free of the museum and appropriating outside space for art.

In the books Sol Lewitt realised as autonomous works, three formal lines of development can be differentiated: the early books mainly contain recordings of conceptual ideas in the form of simple sketches and descriptions; then, books were made in which colour or drawing systems were elaborated using various graphical means of expression; finally, books containing photographs were added, in which temporal and atmospheric aspects convey the concept.

On the occasion of the exhibition, a catalogue designed by Sol Lewitt is published containing a list of all his book-projects. Only those are taken into account, however, which Lewitt regards as autonomous works; therefore the catalogues he designed, as well as small editions containing etchings and screen prints are excluded.